User blog comment:LegionZero/Nero's Parallels to Vergil and Sparda/@comment-72.218.90.59-20140905202554/@comment-108.197.2.39-20140910041711

it was stated that Lady is 10 years older in DMC4 than in DMC3 here

Dante was 19 as of DMC3

from DMC to DMC4 is about a year